1. Field of the Invention
The present invention relates to a timepiece such as a wrist watch or a clock for displaying time information, that is, time information such as an hour, a minute, and a second, and calendar information such as a date, days of the week, a month, and a year by use of a liquid crystal display.
2. Description of the Related Art
Various kinds of timepieces for digitally displaying time information such as an hour, a minute, and a second, and calendar information such as a date, days of the week, a month, and a year by use of a liquid crystal display have been brought to the commercial stage and are being used.
When the time information and the calendar information are digitally displayed by the liquid crystal display, predetermined display is performed by arranging an upper polarizing film and a lower polarizing film at the upper and the lower sides of a liquid crystal cell respectively, and using properties of a liquid crystal layer sealed in the liquid crystal cell in which optical characteristics change when an electrical field is applied thereto.
The timepiece using the conventional liquid crystal display digitally displays the time information and the calendar information in black on a white background in a typical normally white mode.
An example of a conventional timepiece for digitally displaying the time information using the liquid crystal display will be explained here using the drawings.
FIG. 27 is a plan view showing an example of a wristwatch for performing conventional digital display. FIG. 28 is a schematic sectional view taken along line 28xe2x80x9428 in FIG. 27.
In this timepiece, as shown in FIG. 28, a timepiece module composed of a liquid crystal display panel described later and a circuit board 205, and the like are housed in a package composed of a case body 201, a cover glass 202, and a case back 203. A dial cover 231 for shielding a portion of a sealant and the like of the liquid crystal display panel and used for a visual design of the timepiece is provided between the cover glass 202 and the liquid crystal display panel.
The liquid crystal display panel used for digital display includes a first substrate 211, first electrodes 212 formed on an inner face of the first substrate 211, a second substrate 213 opposed to the first substrate 211 with a predetermined gap interposed therebetween, and second electrodes 214 formed on an inner face of the second substrate 213, as viewed from the cover glass 202 side (the visible side of an observer), in which portions where the first electrodes 212 and the second electrodes 214 overlap respectively become display pixels. Normally, a segment type electrode form is used.
A liquid crystal layer 215 is sandwiched between the first substrate 211 and the second substrate 213. The liquid crystal layer 215 is sealed between the first substrate 211 and the second substrate 213 by a sealant 233 and a closing material (not shown). Further, alignment films (not shown) are provided on the opposed inner faces of the first substrate 211 and the second substrate 213 (including top of the first electrodes 212 and top of the second electrodes 214) so as to align the liquid crystal layer 215 in a predetermined direction.
For example, in the case of a liquid crystal layer composed of a twisted nematic liquid crystal, an upper molecular alignment direction of liquid crystal and a lower molecular alignment direction of liquid crystal are oriented orthogonal to each other to thereby set a twist angle thereof to 90 degrees.
Furthermore, a first polarizing film 221 composed of an absorption type polarizing film is provided on the first substrate 211 of this liquid crystal display panel, and a second polarizing film 222 composed of a reflection type polarizing film is provided under the second substrate 213, respectively.
The absorption type polarizing film is an ordinary polarizing film which transmits one of linearly polarized lights of which polarization directions are orthogonal to each other and absorbs the other. The reflection type polarizing film is a polarizing film which transmits one of linearly polarized lights of which polarization directions are orthogonal to each other and for reflects the other, and has been recently developed.
The arrangement of transmission axes of the first polarizing film 221 and the second polarizing film 222 parallel to each other, in combination with the above-described liquid crystal display panel, enables exhibition of a strong reflection state in a case where no voltage or a small voltage is applied to the liquid crystal layer 215, and exhibition of a transmission state in a case where the applied voltage is large.
Further, a light source 207 composed of an electro-luminescent (EL) device and a circuit board 205 for applying a required voltage to the light source 207 and the liquid crystal display panel are disposed on the lower side of the liquid crystal display panel.
The circuit board 205 is connected to the liquid crystal display panel by the use of a zebra-rubber connector 232. The circuit board 205 is connected to the light source 207 also by using a zebra-rubber connector for a light source terminal 239.
The liquid crystal display panel is held by a panel holder 208 and integrated with the circuit board 205 and the like by a circuit holder 209 for holding the circuit board 205 and the like, thereby constituting a timepiece module. A battery 206 is held on the lower side of the circuit board 205.
On the cover glass 202 side of this timepiece, as shown in FIG. 27, a display portion 241 by the above-described liquid crystal display panel is provided, and the display portion 241 includes a morning/afternoon (AM/PM) display portion 242, an hour display portion 243, and a minute display portion 244. Further, an adjustment button 251 for adjusting the time or the like is provided on a side face of the case body 201.
As described above, AM or PM is displayed on the display portion 241, while the hour and the minute are also digitally displayed. In place of the time display, the calendar display such as the year, the month, and the date can be displayed.
However, by simply digitally displaying the typical time information and calendar information as described above, neither variety in design nor interest can be offered, with a resulting tendency to lose soon popularity with consumers, and, as a result, consumption of digital display type timepieces has recently been on the decline.
Further, even in the case where display in a metallic tone can be realized by the use of the reflection type polarizing film as shown in the conventional example, a digital display type timepiece with more variety in visual design has been desired.
Further, it has also been under consideration to shield or open (opening or closing of a shutter) a part or the entire face of the time display portion of the timepiece in accordance with the environment in use or the internal circumstances of the timepiece, but there are problems in making it thinner and in its controllability, and thus it has not been put into practical use yet.
The present invention is carried out in view of such a technical background, and its object is to provide a digital display type timepiece with variety in visual design. Further, another object is to provide a timepiece rich in visual change by opening and closing display on the time display portion in accordance with environments for use of the timepiece, a control signal from a user, or internal circumstances of the timepiece, in addition to improvement of the visual design of the timepiece.
To achieve the above objects, a timepiece according to the present invention is configured so that two liquid crystal display panels and three polarizing films are arranged overlaid one upon another in a case body to form an upper display portion and a lower display portion, and the lower display portion performs at least display on the time and the upper display portion can be used as a shutter.
The configuration will be described hereinafter in more detail.
That is, the timepiece according to the present invention comprises a first liquid crystal display panel constituted by sealing a first liquid crystal layer in a gap between transparent first and second substrates formed with transparent electrodes on opposed inner faces thereof respectively, a second liquid crystal display panel constituted by sealing a second liquid crystal layer in a gap between transparent third and fourth substrates formed with transparent electrodes on opposed inner faces thereof respectively, the second substrate and the third substrate being overlaid one upon another adjacent to each other, and arranged in a case body having a cover glass with the first substrate facing the cover glass side.
A first polarizing film, a second polarizing film, and a third polarizing film are disposed on the cover glass side of the first substrate, between the second substrate and the third substrate, and on the opposite side to the second liquid crystal layer of the fourth substrate, respectively.
The second polarizing film is a reflection type polarizing film which transmits one of linearly polarized lights of which polarization directions are orthogonal to each other and reflects the other.
The first polarizing film, the first liquid crystal display panel, and the second polarizing film constitutes an upper display portion, the second polarizing film, the second liquid crystal display panel, and the third polarizing film constitute a lower display portion, and at least the lower display portion performs display on the time.
In the timepiece, it is preferable that the third polarizing film is also a reflection type polarizing film which transmits one of linearly polarized lights of which polarization directions are orthogonal to each other and reflects the other.
Further, it is preferable that the first polarizing film is an absorption type polarizing film which transmits one of linearly polarized lights of which polarization directions are orthogonal to each other and absorbs the other.
Alternatively, the first polarizing film may be a polarizing film in which an absorption type polarizing film and a reflection type polarizing film are laminated from the cover glass side.
It is preferable to include further a diffusing layer provided between the fourth substrate and the third polarizing film with no diffusing layer provided between the first polarizing film and the second polarizing film.
Further, it is desirable that a space is provided between the second polarizing film and the third substrate. It is preferable that the space is formed by providing a printing layer between the second polarizing film and the third substrate, and the printing layer is used as a panel cover for a time display screen of the lower display portion.
Further, a light source composed of an electro-luminescent (EL) device or the like for emitting light by application of voltage is provided on the opposite side to the fourth substrate with respect to the third polarizing film, thereby enabling display by a transmission illumination under dim external light circumstances. In this case, it is preferable to include a fluorescent ink layer on the light source for absorbing light from the light source and for emitting light with a wavelength different from that of the absorbed light.
It is suitable to arrange the first liquid crystal display panel and the first and second polarizing films so that the upper display portion exhibits a mirror state of reflecting light made incident through the cover glass in a state where no voltage or a voltage at a predetermined value or less is applied to the first liquid crystal layer in the first liquid crystal display panel, and exhibits a transmission state of transmitting the light in a state where a voltage exceeding the predetermined value is applied.
It is also possible that the transparent electrodes are formed on the opposed inner faces of the first and second substrates of the first liquid crystal display panel so that a space between the electrodes opposed with the first liquid crystal layer interposed therebetween changes seamlessly, and that a ratio of a region where the mirror state is exhibited to a region where the transmission state is exhibited in the upper display portion is changed by changing the voltage applied between the opposed electrodes.
It is preferable that, while the upper display portion is exhibiting the mirror state within almost its entire face, the second liquid crystal display panel of the lower display portion is not allowed to perform display on the time.
In this event, it is also preferable that the upper display portion which is exhibiting the mirror state within almost its entire face is allowed to perform part of display on the time such as a second.
The diffusing layer may be a white diffusing plate, and the third polarizing film may be constituted by laminating, from the fourth substrate side, an absorption type polarizing film and a mirror reflector.
The mirror reflector may be a transflective reflector which transmits part of light and reflects almost the other light.
Further, it is possible that the transparent electrodes for applying voltage to the first liquid crystal layer in the first liquid crystal display panel are formed at least in each region of a plurality of regions made by dividing a display region of the upper display portion to apply voltage different in each region to the first liquid crystal layer, and that the upper display portion is configured to be capable of turning into a first state of exhibiting the mirror state within the entire display region, into a second state exhibiting the transmission state or performing part of display on the time such as a second within part of the display region and exhibiting the mirror state within the other region, and into a third state of exhibiting the transmission state within the entire display region.
In this case, it is desirable that while the upper display portion is in the first state or the second state, no voltage or a voltage only at a level at which display is not performed is applied to the second liquid crystal layer in the second liquid crystal display panel of the lower display portion.
The timepiece as described above further comprises a circuit board including a circuit for driving the first liquid crystal display panel and the second liquid crystal display panel in the case body, wherein the first liquid crystal display panel and the second liquid crystal display panel are electrically connected to the circuit board by elastic bodies, respectively, made by alternately laminating conducting portions and insulating portions in a direction orthogonal to a connection direction thereof.
Then, it is preferable that a first elastic body for connecting the first liquid crystal display panel and the circuit board and a second elastic body for connecting the second liquid crystal display panel and the circuit board are arranged along the same edge of the circuit board, and the first elastic body is disposed at an outer periphery side of the circuit board than the second elastic body is.
Alternatively, it is also possible that the elastic body for connecting the first liquid crystal display panel and the circuit board and the elastic body for connecting the second liquid crystal display panel and the circuit board are arranged along one edge and the other edge on two different sides of the circuit board.
Further it is desirable that driving signals applied to the first liquid crystal display panel and the second liquid crystal display panel are signals equal in driving voltage and frequency.
The timepiece according to the present invention enables sophisticated display by laminating the two liquid crystal display panels to constitute the upper display portion and the lower display portion, in combination with the three polarizing films, and by controlling the liquid crystal display panels so that the upper display portion shields (shutter) display contents produced by the lower display portion or display states of the upper display portion and the lower display portion are coordinated.
Further, at least the second polarizing film between the two liquid crystal display panels out of the three polarizing films is composed of a reflection type polarizing film, thereby enabling reflection display and transmission display by the upper display portion. Further, the reflection display is performed in a mirror tone of the same color as that of the case body, thereby visually integrating the case body with the display by the liquid crystal display, improving conventional impression of the liquid crystal display, resulting in improved visual design of the timepiece.
Further, a reflection type polarizing film is used also for the third polarizing film, thereby enabling display by transmission illumination with the light source disposed thereunder and increasing transmittance compared to the case of using a conventional transflective reflector, enabling brighter display.
Furthermore, the first liquid crystal display panel is configured in the entire face electrode structure which enables entire reflection and entire transmission, thereby sharply indicating display such as the time and the like produced by the lower display portion while the upper display portion is in the entire transmission state.
While the upper display portion is in the entire reflection state or a large area thereof is in the reflection state, no voltage or a small voltage is applied to the liquid crystal display panel of the lower display portion to produce uniform display within the entire face, thereby improving the apparent contrast ratio of the upper display portion, even if the state of the lower side can be viewed depending on a viewing angle even through the upper display portion is in the reflection state, enabling uniform display.
When the light source is turned on, at least part of the first liquid crystal display panel is brought into a state voltage applied, thereby improving the apparent contrast ratio, making it difficult for a leak of light due to the first liquid crystal display panel and the polarizing films to be recognized.
Furthermore, the provision of the diffusing layer between the second liquid crystal display panel and the third polarizing film increases the contrast ratio between display by the upper display portion and display by the lower display portion.
When display by the lower display portion is performed using an external light source, the display is performed using light made incident through a portion of the upper display portion with a high transmittance, and thus the third polarizing film is used as a reflector or a reflector is provided on the lower side of the third polarizing film to enable bight display.
Especially, a reflection type polarizing film is used as the third polarizing film and the diffusing layer is provided between the reflection type polarizing film and the fourth substrate of the second liquid crystal display panel, thereby further improving brightness and contrast of display by the lower display portion.